LM2750LD-ADJEV National Semiconductor, LM2750LD-ADJEV Datasheet - Page 3

• Manufacturer Part Number: LM2750LD-ADJEV
• Description: BOARD EVAL LM2750LD-ADJ
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM2750LD-ADJEV

• Main Purpose: DC/DC, Step Up
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 3.8 ~ 5.2V
• Current - Output: 120mA
• Voltage - Input: 2.7 ~ 5.6V
• Regulator Topology: Boost
• Frequency - Switching: 1.7MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM2750
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -
• Lead Free Status / Rohs Status: Not Compliant

Ordering Information
Part Description
The LM2750-ADJ is a switched-capacitor doubler that pro-
duces a low-noise, well regulated output voltage. With a pair
of external resistors, the output voltage can easily be set to
a level between 3.8V and 5.2V. The LM2750 is provided in
National’s 10-pin LLP, a package with excellent thermal
properties that keeps the part from overheating under almost
all rated operating conditions.
A perfect fit for space-constrained, battery-powered applica-
tions, the LM2750 requires only 3 external components: one
input capacitor, one output capacitor, and one flying capaci-
tor. Small, inexpensive ceramic capacitors are recom-
mended for use. These capacitors, in conjunction with the
1.7MHz fixed switching frequency of the LM2750, yield low
output voltage ripple, beneficial for systems requiring a low-
noise supply.
Pre-regulation minimizes input current ripple, reducing input
noise to negligible levels. A tightly controlled soft-start fea-
ture limits inrush currents during part activation. Shutdown
completely disconnects the load from the input. Output cur-
rent limiting and thermal shutdown circuitry protect both the
LM2750 and connected devices in the event of output shorts
or excessive current loads.
References
LM2750 Product Folder and Datasheet:
Application Note 1187 - Leadless Leadframe Package:
http://www.national.com/pf/LM/LM2750.html
http://www.national.com/an/AN/AN-1187.html
LM2750EVAL-ADJ
Order #
3
LM2750LD-ADJ Evaluation Board
Board Usage
INPUT
Connect the input and ground pins of the evaluation board to
a power supply or battery with short, low-impedance, low-
inductace wires or cables. The nominal input voltage range
of the LM2750-ADJ is 2.7V to 5.6V, but at lower output
voltages (Vout
more than 0.7V below the output voltage.
OUTPUT VOLTAGE AND CURRENT
The output voltage of the LM2750-ADJ can be programmed
with a simple resistor divider (see resistors Rfb1 and Rfb2 on
the Evaluation Boad Schematic). The values of the feedback
resistors set the output voltage, as determined by the follow-
ing equation:
In the equation above, the "1.23V" term is the nominal
voltage of the feedback pin when the feedback loop is cor-
rectly established and the part is operating normally. The
sum of the resistance of the two feedback resistors should
be between 15kΩ and 20kΩ:
If larger feedback resistors are desired, a 10pF capacitor
should be placed in parallel with resistor R1.
The output voltage of the LM2750 is guaranteed to accurate
to
nominal operating ratings. Regulation is guaranteed for load
currents as high as 120mA. The LM2750 is capable or
driving load currents up to and above 120mA. The LM2750
datasheet provides information on high load current usage,
and datasheet curves illustrate the typical performance of
the part with output currents as high as 175mA.
SHUTDOWN
A jumper is present on the evaluation board to bring the
LM2750 in and out of shutdown. When the jumper is in
place, the SD pin is connected to V
operational.
Removing the jumper floats the SD pin. A 200kΩ resistor
connected internally between the SD pin and GND pulls the
voltage on the SD pin low. This places the LM2750 in shut-
down.
±
4% when it is set to 5.0V and the part is operated withing
Vout = 1.23V x (1 + Rfb1 / Rfb2)
15kΩ
Description
<
(Rfb1 + Rfb2)
<
4.9V) the input voltage should never be
<
20kΩ
IN
, and the part is
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